Ball bat with a fused end cap

ABSTRACT

A ball bat includes an end cap that is fused directly or indirectly to an inner or outer surface of the bat barrel. In one embodiment, a sleeve is molded or bonded to an inner surface or an outer surface of the bat barrel. The end cap is then fused to the sleeve, optionally via a spin-welding process. If removal of the end cap is attempted, a fracture zone results that damages the end cap and makes it unusable and effectively irreplaceable.

BACKGROUND

Many modern ball bats include a plastic end cap that is either mechanically fixed to the end of the bat barrel or bonded in place. The plastic end cap provides a light weight closure for the end of the bat barrel. Because bat-ball collisions are severe, the end cap and its attachment mechanism must withstand numerous impacts while remaining in place. One issue that commonly arises is that plastic is not easily bondable to fibrous-composite materials or other commonly used bat materials, and the bonding process itself can be unreliable. Mechanical mechanisms that secure the cap to the bat barrel are also often unreliable.

FIG. 1 shows an example of an existing end cap that is mechanically attached to a bat barrel 12. The end cap 10 may be made of an injection-molded thermoplastic material or of another suitable material. Such an end cap 10 typically covers the end 14 of the barrel 12, and the diameter of the outside edge 16 of the cap 10 is substantially equal to the outside diameter 18 of the bat barrel 12. In the illustrated example, the bat barrel 12 includes an inwardly facing groove 26 and an inwardly protruding ridge 22, which are engaged by an outwardly protruding ring 24 and an outwardly facing groove 20 of the end cap 10, respectively. The end cap may additionally or alternatively be bonded to the inner surface of the barrel 12 with an adhesive.

An end cap 10 such as the one shown in FIG. 1 typically can be removed without damaging the ball bat. This removal can be achieved by applying heat or steam to soften the end cap and any adhesive, then pulling the end cap 10 out of the barrel 12 using a gripping device. Once the cap is removed, after-market bat modifiers are able to thin out the barrel 12 from the inside, which yields a more reactive bat barrel (i.e., one that increases the potential power of the bat). Such a modified bat is generally not sanctioned for league play and can be dangerous to fielders due to the increased velocity at which a ball may leave the bat.

Following such an unsanctioned modification, the end cap 10 can typically be re-installed onto the bat barrel 12 such that the internal modification is undetectable. And, in the event the end cap 10 happens to be damaged, a new end cap may be used to replace the original cap. This type of unsanctioned modification has become so prevalent that replacement caps are now available from third-party vendors. Thus, there exists a need for a ball bat that is constructed in a manner that makes undetectable barrel modifications difficult or impossible to achieve.

SUMMARY

A ball bat includes an end cap that is fused directly or indirectly to an inner or outer surface of the bat barrel. In one embodiment, a sleeve is molded or bonded to an inner surface or an outer surface of the bat barrel. The end cap is then fused to the sleeve, optionally via a spin-welding process. If removal of the end cap is attempted, a fracture zone results that damages the end cap and makes it unusable and effectively irreplaceable. Other features and advantages will appear hereinafter. The features described above can be used separately or together, or in various combinations of one or more of them.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, wherein the same reference number indicates the same element throughout the several views:

FIG. 1 is a sectional view of an existing end cap mechanically attached to a bat barrel.

FIG. 2 is a side view of a ball bat with an end cap.

FIG. 3 is an exploded sectional view of a fusible end cap separated from a bat barrel, according to one embodiment.

FIG. 4 is a sectional view of the end cap of FIG. 3 fused to an inner sleeve in the bat barrel.

FIG. 5 is a sectional view of an inner sleeve being injection molded to the inner surface of a bat barrel, according to one embodiment.

FIG. 6 is a sectional view of an inner sleeve that is injection molded to an inner surface of a bat barrel as a result of the process illustrated in FIG. 5.

FIG. 7 is an exploded sectional view of an end cap separated from a bat barrel, according to another embodiment.

FIG. 8 is a sectional view of the end cap of FIG. 7 after being spin-welded to an inner surface of the bat barrel.

FIG. 9 is a sectional view of an end of a bat barrel configured to receive an outer sleeve.

FIG. 10 is a sectional view of the bat barrel of FIG. 9 with an outer sleeve attached to the barrel.

FIG. 11 is a sectional view of the bat barrel shown in FIGS. 9 and 10 with an end cap fused to the outer sleeve.

DETAILED DESCRIPTION OF THE DRAWINGS

Various embodiments of the invention will now be described. The following description provides specific details for a thorough understanding and enabling description of these embodiments. One skilled in the art will understand, however, that the invention may be practiced without many of these details. Additionally, some well-known structures or functions may not be shown or described in detail so as to avoid unnecessarily obscuring the relevant description of the various embodiments.

The terminology used in the description presented below is intended to be interpreted in its broadest reasonable manner, even though it is being used in conjunction with a detailed description of certain specific embodiments of the invention. Certain terms may even be emphasized below; however, any terminology intended to be interpreted in any restricted manner will be overtly and specifically defined as such in this detailed description section.

Where the context permits, singular or plural terms may also include the plural or singular term, respectively. Moreover, unless the word “or” is expressly limited to mean only a single item exclusive from the other items in a list of two or more items, then the use of “or” in such a list is to be interpreted as including (a) any single item in the list, (b) all of the items in the list, or (c) any combination of items in the list. Further, unless otherwise specified, terms such as “attached” or “connected” are intended to include integral connections, as well as connections between physically separate components.

Turning now in detail to the drawings, as shown in FIG. 2, a baseball or softball bat 1, hereinafter collectively referred to as a “ball bat” or “bat,” will be shown and described. The ball bat 1 includes a handle 2, a barrel 4, and a tapered section 6 joining the handle 2 to the barrel 4. The free end of the handle 2 includes a knob 8 or similar structure. The barrel 4 is closed off by an end cap 9, as described in detail below. The interior of the bat 1 is preferably hollow, allowing the bat 1 to be relatively lightweight so that ball players may generate substantial bat speed when swinging the bat 1.

The ball bat 1 may be a one-piece construction or may include two or more separate attached pieces (for example, a separate handle and barrel), as described, for example, in U.S. Pat. No. 5,593,158, which is incorporated herein by reference. The barrel 4 may be made of a composite material, such as carbon or glass, or of a metal material, such as aluminum. The bat handle 2 may be constructed from the same material as, or different materials than, the barrel 4. In a two-piece ball bat, for example, the handle 2 may be constructed from a composite material (the same or a different material than that used to construct the barrel), a metal material, or any other suitable material.

The bat barrel 4 may include a single-wall or multi-wall construction. A multi-wall barrel may include, for example, barrel walls that are separated from one another by one or more interface shear control zones (“ISCZs”), as described in detail in U.S. Pat. No. 7,115,054, which is incorporated herein by reference.

The ball bat 1 may have any suitable dimensions. The ball bat 1 may have an overall length of 20 to 40 inches, or 26 to 34 inches. The overall barrel diameter may be 2.0 to 3.0 inches, or 2.25 to 2.75 inches. Typical ball bats have diameters of 2.25, 2.625, or 2.75 inches. Bats having various combinations of these overall lengths and barrel diameters, or any other suitable dimensions, are contemplated herein. The specific preferred combination of bat dimensions is generally dictated by the user of the bat 1, and may vary greatly between users.

The embodiments described below are generally directed to a ball bat including an end cap that is fused directly or indirectly to an inner surface of the bat barrel. For example, a sleeve to which the end cap may be fused may be bonded to or molded with an inner surface of the bat barrel. Fused, as used herein, generally refers to a solid-state bond that is achieved by melting two compatible components together, such as two components made of thermoplastic or composite materials. Polyester is one particularly suitable thermoplastic material, since polyester is bondable to the epoxy resin that forms a typical composite bat barrel. Other suitable materials include polyurethane, polycarbonate, polyamide, polypropylene, or the like.

In one embodiment, an inner sleeve in a composite bat barrel is formed and attached during molding of the barrel. This may be achieved by fusing the outer surface of the sleeve to the inner surface of the composite barrel while heat and pressure are applied in the mold. Composite bat barrels are generally formed with plies of fiber-reinforced preimpregnated materials that are rolled into a tubular shape. A bladder is placed inside the preimpregnated tube and the assembly is placed in a mold. Air fittings may be applied to the bladder ends. The mold is then closed and heated, and air pressure is applied to the bladder to force the preimpregnated plies against the mold, which consolidates and cures the plies.

The sleeve may be placed between the bladder and the innermost ply so that, when pressure is applied during the molding process, the sleeve compresses against the innermost ply and bonds to its epoxy resin, which flows along the sleeve. Once the epoxy crosslinks and cures, the sleeve is molded to the inner surface of the barrel.

Alternatively, the sleeve may be bonded to the inner surface of an already cured bat barrel via an adhesive. This may be preferred when the barrel material is aluminum or another metal, or the bat material necessitates that an adhesive be used to bond the inner surface of the barrel to the sleeve. In one embodiment, an adhesive is positioned between the inner surface of the bat barrel and the outer surface of the sleeve. Pressure may then be applied to the inner sleeve to compress the adhesive and complete the bonding process.

The sleeve may alternatively be a sheet of plastic or similar material that is rolled into a cylindrical shape and then placed inside the rolled preimpregnated plies of the bat barrel. When forming the barrel, the heat and consolidation pressure will force the rolled up sheet to bond to the thermosetting resin of the preimpregnated plies, permanently fixing the inner sleeve to the inside surface of the bat barrel.

In another embodiment, the sleeve may be injection-molded to the inner surface of the bat barrel. Such a process involves placing the barrel in an injection mold that seals against an outer surface of the barrel. A sliding core may then be positioned inside the barrel near or against the barrel's inner surface. Plastic is then injected between the inner surface of the barrel and the sliding core to form the sleeve.

The inner sleeve may additionally or alternatively include ridges, grooves, holes, or other surface effects for mechanically locking the sleeve in place to corresponding or complementary features in the bat barrel.

When used, the inner sleeve may have any suitable dimensions. In one embodiment, the inner sleeve has a thickness of approximately 0.03-0.07 inches, and a length of approximately 0.25-0.75 inches. The inner sleeve may form a complete cylinder or may optionally have a gap along its length to allow the sleeve to expand against the preimpregnated plies during molding. The inner sleeve is preferably made of the same material or a similar material to the end cap so that it may thermally bond to the end cap. The inner sleeve is also preferably bondable or moldable to the resin of the composite barrel.

In another embodiment, the barrel itself may be formed of a thermoplastic material or of a similar material such that the end-cap material is compatible with, and fusible to, the resin of the bat barrel. In this embodiment, the end cap may be directly fused to an inner surface or outer surface of the barrel such that no sleeve is required.

In one embodiment, the end cap is fused to the inner sleeve or to the inner surface of the bat barrel via spin-welding. Spin welding is a process in which friction is created by spinning one component relative to another component, such as two thermoplastic components, and forcing them together. The heat from the friction melts the two materials creating a solid-state bond between them. The end cap is preferably somewhat flexible and has an outer diameter that is slightly larger than the inner diameter of the bat mating surface, such as the inner surface of the barrel or the inner sleeve, to create the necessary interference and friction.

This spin-welding process fuses the end cap to the inner sleeve or to the inner surface of the bat barrel. Removal of such a fused end cap would be very difficult and would result in significant damage or destruction to the end cap itself. Further, any “successful” removal of the end cap would create a fracture zone in the bat barrel or on the inner sleeve, making it effectively impossible to successfully attach or affix another end cap to the fracture zone.

Various specific embodiments will now be described. It is to be understood, of course, that other embodiments utilizing the inventive concepts described herein may alternatively be employed.

Turning to FIGS. 3 and 4, in one embodiment, a sleeve 30 is permanently bonded, molded, or otherwise attached to an inner surface of a bat barrel 12. A flexible end cap 29 includes a ridge or a protruded ring 28 with an outer diameter that is greater than the inner diameter of the inner sleeve 30 before the end cap 29 is inserted into the barrel 12. The end cap 29 and the inner sleeve 30 are made of similar or identical materials, such as thermoplastic or other suitable materials, so that, when abraded together during a spin-welding process, for example, they form a solid-state bond between them. At a minimum, the end cap 29 is made of a material that is compatible with the barrel's resin so that a thermal bond between them may be achieved during a spin-welding or similar process.

In one embodiment, the inner sleeve 30 may be formed prior to its fusion to the barrel 12 by injection molding it into a substantially cylindrical form that includes an outer diameter that essentially matches the inner diameter of the bat barrel 12. The inner sleeve 30 may additionally or alternatively include one or more grooves into which epoxy may flow, or one or more ridges 34 that engage corresponding grooves or channels in the inner surface of the bat barrel 12, to provide a mechanical lock to the barrel 12. The inner sleeve 30 may optionally include a gap along its length that allows the inner sleeve 30 to expand during the molding process.

In one embodiment, the inner sleeve 30 may be bonded to the inner surface 32 of the barrel 12 during the molding process. The inner sleeve 30 may be positioned on the inside of the barrel pre-form during packing of the mold. When the mold is heated and air pressure is applied to consolidate the preimpregnated barrel plies, the inner sleeve 30 is pressured against the plies such that it bonds to their epoxy resin.

The inner sleeve 30 effectively forms at least a portion of the inner material of the barrel 12. Fusing the end cap 29 to the inner sleeve 30 may occur anytime during the manufacturing process, but will typically occur after the barrel 12 is finished and decorated. The process of spin welding lends itself well to fusing the end cap 29 to the inner sleeve 30. This process involves clamping or otherwise fixing the bat barrel 12 in place while spinning the end cap 29 at a high rotational speed and inserting it into the bat barrel 12. To spin weld the end cap 29 to the inner sleeve 30 or inner surface of the bat barrel 12, the cap 29 is spun at a velocity of approximately 2500-3500 rpm, or approximately 3000 rpm.

In the embodiment illustrated in FIGS. 3 and 4, the protruded ring 28 of the end cap 29 comes into contact with the inner sleeve 30 and their thermoplastic (or other similar) materials melt together from the heat generated by the friction between them. The end cap 29 continues to be inserted into the barrel 12 until a shoulder 36 on the end cap 29 contacts the end of the bat barrel 12. The melt region 38 of the two components then solidifies such that the end cap 29 becomes permanently fused to the bat barrel 12. Any excess resin or flash may optionally be collected in a relief area 31. A second relief area may optionally be included at the handle end of the melt region 38.

FIG. 4 illustrates the end cap 29 fused to the bat barrel 12 in the finished state. The protruded ring 28 of the end cap 29 has melted and fused with the inner sleeve 30 in the melt region 38. Excess flash is provided in the relief area 31. The volume of the melt region 38 may vary based on the materials used, the desired strength of the attachment, and the desired weight properties of the ball bat. If such a fused end cap 29 is removed, the melt region 38 will fracture. The resulting fracture zone will have a rough and inconsistent surface, making it effectively impossible to reattach the end cap 29 or to attach a replacement end cap. Further, there will be no useable mechanical mechanism remaining to which an end cap may be attached.

FIGS. 5 and 6 illustrate an embodiment in which an inner sleeve 40 is injection molded to the inner surface of a metal barrel, such as an aluminum barrel 42. The aluminum barrel 42 includes a ridge or an inwardly protruding ring 44 and a groove 46. Other mechanical means may be used to lock the inner sleeve 40 to the aluminum barrel 42. For example, additional grooves or protruding rings may be utilized. Additionally or alternatively, holes may be drilled in the wall of the barrel for receiving protrusions on the inner sleeve.

The barrel 42 is positioned in an injection mold where an exterior portion 48 of the mold compresses and seals to the outside surface 50 of the barrel 42. An internal core 52 is then inserted into the barrel to compress and seal against the protruding ring 44 and the end 55 of the barrel 42. A polymer resin is injected into a space 53 formed between the inner surface 54 of the barrel 42 and the outer surface 56 of the internal core 52 to form the internal sleeve 40. The injected polymer flows into the groove 46 to provide a mechanical lock.

FIG. 6 illustrates the inner sleeve 40 molded to the barrel 42 via the injection-molding process shown in FIG. 5. The polymer has formed in the groove 46 to provide a mechanical lock preventing the inner sleeve 40 from being removed. The weld zone between a subsequently added end cap and the inner sleeve 40 may be located anywhere along the length of the inner sleeve 40. Removal of such an end cap will result in a rough and inconsistent fracture zone making replacement of the cap effectively impossible.

FIGS. 7 and 8 illustrate another embodiment in which an end cap 74 is attached to a metal barrel, such as an aluminum barrel 60. The aluminum barrel 60 includes an inwardly protruding ridge or rim 62 and an inwardly protruding receiving portion or forming portion 64. The rim 62 includes an inner edge 66 that has a smaller diameter than the inside surface 68 of the barrel 60. The forming portion 64 includes a curved portion 70 and an inside edge 72. The diameter of the inside edge 72 is smaller than the inside diameter of the rim edge 66.

The end cap 74 includes a cylindrical or substantially cylindrical extension 76. The end cap 74 is spun at a high rate of speed of approximately 2500-3500 rpm, or approximately 3000 rpm, and is inserted into the barrel 60. When the end-cap extension 76 comes into contact with the curved portion 70 of the barrel 60, the thermoplastic (or similar) material of the end cap 74 begins to soften and deform. The deforming extension 76 is then guided by the curved portion 70 into a cavity 78 under the rim 62 such that the end cap 74 is secured in place. FIG. 8 illustrates the installed end cap 74 with the deformed extension 80 filling the cavity 78 and locking the end cap 74 into position.

In another embodiment, the bat barrel may include an external recess or zone for receiving a sleeve to which an inner surface of an end cap may be fused or otherwise attached. Such a configuration is particularly applicable to a metal bat barrel but may also be utilized in a composite bat barrel. The end of the bat barrel may be formed by machining in the case of a metal bat, or by molding in the case of a composite bat.

FIGS. 9-11 illustrate an example of such an embodiment. A bat barrel 90 includes a recessed channel or groove 92 bordered by a rim 94 or other outward projection. A sleeve 100 is molded or otherwise attached to an outer surface of the groove 92. An end cap 110 is fused or otherwise attached to the outer sleeve 100 at a weld region 112 formed between an inner surface of the end cap 110 and an outer surface of the sleeve 100.

The outer sleeve 100 may be a conformable C-shaped ring, such as a thermoplastic ring, that may be pulled open to clear the rim 94 and to seat on a floor 102 of the groove 92. Alternatively, the sleeve 100 may be made of two or more separate pieces that are positioned along the outer circumference of the groove 92. A spin-welding or similar process ideally fuses any open seams to form a one-piece ring fused to the end cap 110.

In the illustrated embodiment, optional holes 96 or openings are drilled through the wall 98 of the bat barrel 90 in the groove region. The outer sleeve 100 includes one or more protuberances 104 that fit into one or more of the holes 96. Such a protuberance 104 aids in preventing rotation of the outer sleeve 100 when the end cap 110 is spin-welded or otherwise attached to it. The free end of the protuberance 104 may optionally be heat-staked to an inside wall 106 of the bat barrel 90.

Any of the above-described embodiments may be used alone or in combination with one another. Further, the end cap and related attachment mechanisms may include additional features not described herein. While several embodiments have been shown and described, various changes and substitutions may of course be made, without departing from the spirit and scope of the invention. The invention, therefore, should not be limited, except by the following claims and their equivalents. 

What is claimed is:
 1. A ball bat, comprising: a handle; a barrel attached to or integral with the handle; a sleeve attached to or integral with a surface of the barrel; and an end cap positioned at an end of the barrel and fused to the sleeve.
 2. The ball bat of claim 1 wherein the end cap and the sleeve comprise substantially similar materials such that they are fusible to each other.
 3. The ball bat of claim 2 wherein the end cap and the sleeve each comprise thermoplastic materials.
 4. The ball bat of claim 3 wherein the barrel comprises a composite material, and the thermoplastic sleeve is molded or bonded to an inner surface of the composite barrel.
 5. The ball bat of claim 3 wherein the barrel comprises a composite material, and the thermoplastic sleeve is molded or bonded to an outer surface of the composite barrel.
 6. The ball bat of claim 1 wherein the end cap is fused to an inner surface of the sleeve.
 7. The ball bat of claim 1 wherein the end cap is fused to outer surface of the sleeve.
 8. The ball bat of claim 1 wherein the sleeve is injection-molded to the inner surface of the barrel.
 9. The ball bat of claim 8 wherein one of the sleeve and the inner surface of the barrel includes a protrusion, and the other of the sleeve and the inner surface of the barrel includes a corresponding groove into which the protrusion is positioned to mechanically secure the sleeve to the inner surface of the barrel.
 10. The ball bat of claim 1 wherein one of the sleeve and the surface of the barrel includes a protrusion, and the other of the sleeve and the surface of the barrel includes a corresponding groove into which the protrusion is positioned to mechanically secure the sleeve to the surface of the barrel.
 11. A ball bat, comprising: a handle; a barrel including a first end attached to or integral with the handle and a second distal end, with the barrel including an inwardly projecting rim at the second distal end and an inwardly projecting forming portion spaced from the rim to define a cavity between the rim and the forming portion; and an end cap including a deformable extension positioned in the cavity under the rim such that the end cap is secured to the barrel.
 12. The ball bat of claim 11 wherein the barrel comprises a metal material and the end cap comprises a deformable material.
 13. The ball bat of claim 12 wherein the end cap comprises a thermoplastic material.
 14. The ball bat of claim 11 wherein the forming portion includes a curved portion that positions the deformable extension in the cavity.
 15. A method of attaching an end cap to a barrel of a ball bat, comprising: attaching a sleeve to an inner surface of the barrel; spinning the end cap at a high velocity; inserting the spinning end cap into the barrel so that an outer region of the end cap spins against an inner surface of the sleeve; and fusing the outer region of the end cap to the sleeve via the heat and friction generated between them.
 16. The method of claim 15 wherein the attaching step comprises molding the sleeve to the inner surface of the barrel.
 17. The method of claim 15 wherein the attaching step comprises bonding the sleeve to the inner surface of the barrel.
 18. The method of claim 15 wherein the spinning step comprises spinning the end cap at a velocity of approximately 3000 rpm.
 19. The method of claim 15 wherein the inserting step continues until a shoulder on the end cap contacts an end of the barrel.
 20. A ball bat, comprising: a handle; a barrel attached to or integral with the handle, the barrel comprising a first fusible material; and an end cap comprising a second fusible material that is compatible with the first fusible material, the end cap directly fused to the barrel. 